Specifies the analysis date, the start date of a forecast (base date) or observation date.


Valid formats are:

  • Absolute as YYYY-MM-DD, YYYYMMDD. The day of the year can also be used: YYYY-DDD
  • Relative as -n ; n is the number of days before today (i.e., -1 = yesterday )
  • Name of month (e.g. January for Climatology data)
  • Operational monthly means are retrieved by setting day (DD) to 00.


date = 20180918/20180919     # The 18th and 19th September 2018

date = 2018-145              # The 145th day in 2018

date = 20180101/to/20180131  # Every day in September 2018

date = -2                    # The day before yesterday 

For ODB data the date refers to the ODB column andate, i.e. the date of the assimilation run.